Device for the loading of bore holes with explosive



Sept. 28, 1965 B. A. KIHLSTRGM ETAL 3,203,381

DEVICE FOR THE LOADING OF BORE HOLES WITH EXPLOSIVE Filed Dec. 11, 1962 z E I w INVENTORS ATTORNEYS VIII III/III United States PatentOffice 3,208,381 Patented Sept. 28, 1965 3,208,381 DEVICE FOR THE LOADING F BORE HOLES WITH EXPLOSIVE Bjorn Assar Kihlstriim, Hagcrsten, and Nils Giista Larsson, Stockholm, Sweden, assignors to Nitroglycerin Aktiebolaget, Gyttorp, Sweden, a corporation of Sweden Filed Dec. 11, 1962, Ser. No. 243,866 3 Claims. (Cl. 102-30) This invention relates to a device for use in the loading of bore holes with explosive.

More particularly this invention relates to a device for use in the loading of bore holes with explosive encased in bar-shaped or tubular packages. Such bar-shaped packings of explosive are employed, for example, in blasting of parallel hole taps, in blasting pipe trenches, in column charging and in the so-called smooth-blasting. When, for example, a tunnel is blasted out, it is of great importance that the roof and end walls become as smooth and free from fissures as possible. In order to obtain this result the blasting must be carried out with small quantities of explosive per length unit of bore hole since otherwise fissures would be formed in the row of blast holes. For this reason in said type of blasting operations, for example, packages in the shape of bars or tubes with a considerably smaller diameter than that of the bore holes in the rock are used. This feature gives rise to the difliculty that the explosive containing packages are easily forced out of holes located adjacent the holes where the detonation is just occurring due to gas flowing through fissures in the rock into the firstmentioned holes.

One main object of the invention is to overcome said difliculty by providing bar-shaped or tubular packages of explosive having means adapted to counteract said tendency of the packages to become forced out of the bore holes by gases penetrating into said holes.

Another object of the invention is to provide barshaped or tubular packages of explosive having separate means adapted to anchor the packages in the bore holes on connection of said packages with said separate means.

Further objects and advantages of the invention will become apparent from the following description, considered in connection with the accompanying drawing, which forms part of this specification, and of which:

FIG. 1 is a diagrammatic representation of a portion of a tunnel roof with bore holes formed therein.

FIG. 2 is a partly sectional view of a portion of a bore hole with bar-shaped or tubular explosive containing package located therein and united to one another by means of a jointing sleeve formed according to the invention.

FIG. 3 is a perspective view of a bar-shaped explosive containing package with a sleeve as shown in FIG. 2 attached thereto.

Inserted into bore holes are bar-shaped explosive charges which consist of a tubular package 12 encasing an explosive. The bars or tubes have so small a diameter that only part of the cross-sectional area of the bore hole is occupied by the charge.

One end of a package 12 carries a sleeve generally denoted 14. This sleeve has a cylindrical portion 16 of a size to receive snugly the end of the package. The end of the package maybe closed by a transverse inner Wall 18 formed in the sleeve.

The sleeve 14 is made of synthetic or natural plastic, metal or a similar material possessing some elasticity. The free end of the sleeve is formed with longitudinal slots 20 defining tongues or fingers 22 which preferably extend axially and near the closed end of the slots the sleeve has a reduced portion 24 of slightly smaller diameter than the outer diameter of the explosive containing tubular package 12. The tongues 22 may with their outer portions be located within a diameter which is only slightly greater than the inner diameter of the tubular packages so that the latter may easily and tightly be packed in cardboard boxes for transport to the blasting place. When, however, another package 26 is introduced between the tongues 22 and forced through the restricted portion 24 the tongues are resiliently bent outwards. In this condition the tongues with their end portion occupy a diameter enlarged so much as to cause them to bear against the wall of the bore hole 10. This implies that on insertion of the packages 12, 26 joined by the sleeve 14 into the hole 10 in the direction indicated in FIG. 2 by the arrow 28 the tongues are brought to bear against the hole wall and thereby to lock the tongues against movement outwards out of the hole. In this Way the packages are kept in position even if the holes extend in an upward direction and if during a short interval blasting operation with many charges fissures are created in the bed-rock through which gas developed by the first explosions and having superatmospheric pressure is momentarily leaking into holes charged but not yet blasted. By various shape of the tongues or fingers the location of the charge in the bore hole may be influenced in a desired direction, for example by arranging the tongues along a circle so that the explosive containing bar-shaped packages are centered in the bore holes which additionally contributes to providing a lenient blasting which renders a smooth and fissure-free rock surface.

By forming the sleeve or the tongues thereof so as to permit gases from adjacent holes to pass them improved safety for correct operation of the sleeve of the invention is obtained.

The sleeves 14 may constitute separate units which separately from the bar-shaped packages are introduced into the holes from the mouths thereof. From the point of view of loading, however, insertion of a plurality of explosive containing packages jointed together by means of sleeves formed according to the invention are preferred. The tongues may also constitute a direct continuation of the tubular explosive containing package and thus be made integral with the same. The resilient sleeve may also have an annular or hopper resembling shape. The tongues or fingers proper may be rigid and supported by resilient members tending to move them into the spurning or locking position.

While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the amended claims.

What we claim is:

1. A device for connecting tubular packages of explosives for the loading of bore holes slightly larger in diameter than the packages comprising a generally tubular sleeve constructed of resilient material, said sleeve having an inner diameter of a size to snugly receive one end of a package of explosives, a transverse wall intermediate the ends of said sleeve and forming a stop for said packages, one end of said sleeve having a reduced portion of a diameter less than the diameter of said packages and spaced from said transverse wall, said one end of the sleeve having a plurality of slots extending from the end thereof through said reduced portion and forming a plurality of tongues, whereby when a second package is inserted in said one end of said sleeve the package will engage said reduced portion and expand said tongues outwardly into engagement with the walls of said bore holes to resist movement of the packages of explosives in one direction.

2. The structure of claim 1 in which the free end portion of said one end is substantially the same diameter as the other end when said tongues are not expanded.

3. A device for connecting multiple cylindrical members of substantially equal diameter and maintaining said members in concentric relation within a bore comprising a generally tubular elongated sleeve having at least one end portion constructed of resilient material, said sleeve having an inner diameter of a size snugly to receive said cylindrical members, a transverse wall in said sleeve spaced from the other end of said sleeve and forming a stop for said members, said one end portion having a portion of reduced inner diameter spaced from said transverse wall and having a plurality of longitudinal slots extending from the end of said sleeve through the portion of reduced diameter and forming a plurality of fingers, whereby a first cylindrical member can be inserted in the other end of said sleeve until it engages one side of said transverse wall and a second cylindrical member can be inserted in said one end portion References Cited by the Examiner UNITED STATES PATENTS 2,082,112 6/37 Layne et a1. 166-206 X 2,550,591 10/48 Parsons 285-319 2,491,692 12/49 Shimek 10221.8 2,704,031 3/55 Taylor 102-218 2,876,700 3/59 Householder 10230 FOREIGN PATENTS 25,121 12/01 Switzerland.

493,667 3/30 Germany.

977,180 11/50 France. 1,062,032 12/53 France.

SAMUEL FEINBERG, Primary Examiner. 

3. A DEVICE FOR CONNECTING MULTIPLE CYLINDRICAL MEMBERS OF SUBSTANTIALLY EQUAL DIAMETER AND MAINTAINING SAID MEMBERS IN CONCENTRIC RELATION WITHIN A BORE COMPRISING A GENERALLY TUBULAR ELONGATED SLEEVE HAVING AT LEAST ONE END PORTION CONSTRUCTED OF RESILIENT MATERIAL, SAID SLEEVE HAVING AN INNER DIAMETERS OF A SIZE SNUGLY TO RECEIVE SAID CYLINDRICAL MEMBERS, A TRANSVERSE WALL IN SAID SLEEVE SPACED FROM THE OTHER END OF SAID SLEEVE AND FORMING A STOP FOR SAID MEMBERS, SAID ONE END PORTION HAVING A PORTION OF REDUCED INNER DIAMETER SPACED FROM SAID TRANSVERSE WALL AND HAVING A PLURALITY OF LONGITUDINAL SLOTS EXTENDING FROM THE END OF SAID SLEEVE THROUGH THE PORTION OF REDUCED DIAMETER AND FORMING A PLURALITY OF FINGERS, WHEREBY A FIRST CYLINDRICAL MEMBER CAN BE INSERTED IN THE OTHER END OF SAID SLEEVE UNTIL IT ENGAGES ONE SIDE OF SAID TRANSVERSE WALL AND A SECOND CYLINDRICAL MEMBER CAN BE INSERTED IN SAID ONE END PORTION UNTIL IT ENGAGES THE OUTER SIDE OF SAID TRANSVERSE WALL AND SAID SECOND MEMBER WILL ENGAGE SAID PORTION OF REDUCED DIAMETER AND MOVE SAID FINGERS RADIALLY OUTWARDLY. 